The poultry industry has recently made significant advances in dealing with many of its problems. However, one problem area which has met with little success is the effort to decrease the incidence of broken hens' eggs. Approximately 5-8% of eggs laid by hens are prematurely broken with a loss to egg producers of up to $100 million dollars or more per year. Generally, the reason for the premature breakage appears to be insufficient calcification of the egg shell, a condition which produces an egg shell which is too thin to withstand forces exerted upon it. It is well known that Vitamin D.sub.3 affects the shell thickness of hens' eggs. However, Viatmin D.sub.3 has little or no effect on the thickness of egg shells from some hens. Furthermore, the activity of Vitamin D.sub.3 for increasing shell thickness reaches a plateau which does not show an increase even at extremely high dosages of Vitamin D.sub.3.
Recently an active metabolite of Vitamin D.sub.3 has been isolated. This metabolite, the 25-hydroxy derivative of Vitamin D.sub.3, generically known as 25-hydroxycholecalciferol, and referred to hereafter as 25-HCC, has been shown to be more active than Vitamin D.sub.3 in the rat line rickets cure assay and in the rickets prevention assay in young chicks.
However, no particular tests using 25-HCC in mature egg-laying chickens or other species are disclosed in the prior art. Perhaps of even greater significance, only problems dealing with bone calcification such as rickets and osteomalacia, or general membrane calcium transport, such as cattle milk fever and hypoparathyroidism in humans have been dealt with by the art.
The increasing of hen egg shell thickness and the curing or preventing of bone conditions such as rickets and osteomalacia proceed by different physiological mechanisms of action. The substance which is responsible for increasing shell thickness is calcium carbonate. The substance deposited which aids in treating the various bone diseases is calcium hydroxyapatite, a complex mineral-like salt of phosphorus, oxygen, and calcium which is chemically unrelated to carbonate. Furthermore, the organic matrices in which each of these substances is deposited differ radically from each other. Egg shell organic matrix is comprised of noncellular amorphous sheets of protein. The bone organic matrix is formed, living tissue capable of reproducing itself.